1. Field of the Invention
Vine fruit such as grapes have been grown and trained on trellis structures for decades. In the heretofore typical case, wooden posts, or stakes, are driven into the ground, and a cross arm is nailed to the post near the top thereof. The posts are arranged in rows, and each row is (now) spaced from its adjacent row by a distance sufficient to permit mechanized equipment, such as a tractor, to operate between rows. The same spacing also provides easy access to the vines for workers who prune, train the vines and pick the fruit.
More recently, the use of steel posts has become popular. The steel posts do not rot below the soil line, and they do not break off under loading, which increases as the fruit develops and matures. Thus, while the steel posts cost more than wooden posts, maintenance is materially reduced, and utility enhanced.
It is not realistic, however, to drive a nail or a staple into a steel post in order to secure trellis wires to them or the cross arms attached to them. It is workable, but impractical to attempt to manually tie each wire to a post or cross arm individually and, to some extent, it defeats the purpose of the modem trellis system which is intended to be significantly less labor intensive.
2. Overview of the Prior Art
The system of the present invention has particular, although not exclusive, utility in the novel trellis configuration taught in Parrish et al. U.S. Pat. No. 5,797,214, wherein steel posts and cross arms support trellis wires upon which vines are trained for, inter alia, mechanical harvest.
A form of wire retainer is shown in Pasztor U.S. Pat. No. 3,197,919 as number 7 and is in the nature of a staple. In Boal U.S. Pat. No. 4,223,872 the post is slotted to receive a wire. However, when a "T" post is used, slotting such as this would weaken the post and defeat the purpose of its use.
Roberts U.S. Pat. No. 3,791,070 suggests the use of retaining hooks 32, 34 and 36, but in Roberts the hooks are integrally formed with the cross beam 12 and would be unsuitable for use in a trellis system such as that for which the present invention is readily adapted. Gailbraith U.S. Pat. No. 5,438,795 suggests straps with slots provided for the receipt of wire, but there remains the very real problem of how to attach these straps to a steel post, such as a "T" post.
In truth, the heretofore accepted method of securing wire to a steel post by individually tying the same at each point of connection, appears to be a docile resignation to popular taste, at least until the advent of the present invention.